With the rapid development of communications technologies, the future development trend of communications networks is that a variety of wireless communications networks coexist and develop, and therefore heterogeneous network deployment is gradually introduced in a wireless network.
In heterogeneous network deployment, network coverage is formed by cells of different sizes and types, such as macrocells, small cells, and microcells. A macrocell has a large and continuous coverage area, and seamless coverage is formed between macrocells. Within the coverage of a macrocell, several low-power nodes, such as a small base station, a home base station, a relay station and a wireless local area network access point, are usually deployed. Because these low-power nodes have small wireless coverage areas, they are referred to small cells; that is, the coverage of a macrocell includes the coverage of a plurality of small cells, and in heterogeneous network deployment, small cells are scattered in a macrocell. By means of the structure of heterogeneous network deployment, the network traffic volume is large; for example, the traffic is heavy, and, when a macrocell is under heavy network load, a network service can be distributed by switching a terminal to a corresponding small cell, thereby increasing the network capacity.
During heterogeneous network deployment, according to different demands of carriers, a macrocell and a small cell can be set to different frequencies, and the small cell is an inter-frequency cell for the macrocell. In such an inter-frequency deployment, a network side device of the macrocell, when needing to switch a terminal to an inter-frequency cell at a band, needs to trigger the terminal to perform inter-frequency cell measurement, and the terminal, when determining that a signal of the inter-frequency cell meets a specific measurement event, reports the inter-frequency cell to the network side device, making it easy for the network side device to perform cell handover.
When a terminal performs inter-frequency cell measurement, neither data nor signaling is transmitted between the terminal and a network side device, and a measurement process usually takes a long time. Therefore, to prevent influences on normal communications services, the terminal usually performs inter-frequency cell measurement in a discontinuous measurement manner, that is, a gap mode measurement manner, in which a cell signal is measured only within a measurement gap period and normal communications can be performed outside the gap period. Both the network side device and the terminal need to work based on the gap mode to ensure time synchronization.
In an existing method for inter-frequency cell measurement, a network side device determines relevant measurement time parameters of a gap mode, including a gap duration, a gap repetition cycle, a minimum available measurement time, and the like. The relevant measurement time parameters of the measurement gap mode are usually fixed numerical values. For example, the gap duration is 6 ms, the gap repetition cycle is 40 ms, and it is specified that the minimum available measurement time within a certain time is not lower than 60 ms, and the like. Next, the network side device requests that the terminal performs measurement for an inter-frequency cell at a band and sends the relevant measurement time parameters of the gap mode to the terminal. The terminal is then capable of performing, based on the time specifications of the relevant measurement time parameters of the gap mode, measurement on the cell only within the measurement gap period, so as to monitor whether a signal of the inter-frequency cell meets a measurement event, and reports the inter-frequency cell that meets the measurement event to the network side device.
However, it is a continuous process for a terminal to perform inter-frequency cell measurement, and the process stops when a measurement termination instruction from the network side device is received. During the implementation of the present invention, the inventor finds that the prior art at least has the following problem: in heterogeneous network deployment, because of the deployment position relationship of inter-frequency cells and the relationship of different bands where the cells are located, if measurement is performed based on general gap mode measurement time parameters, any inter-frequency cell that meets a measurement event might fail to be measured, and a terminal might perform measurement continuously without receiving a measurement termination instruction, which causes a waste of measurement time and accordingly increases the power consumption of the terminal.